The government has tabled a last-minute amendment to its controversial justice and security bill, conceding that secret hearings cannot be extended further solely by ministerial decree.

The change follows criticism this week from parliament's joint committee on human rights of the order-making powers contained in legislation that expands so-called "closed material procedures", or secret hearings, into civil courts.

The amendment came just before the deadline for submitting alterations to the bill, which will be voted on for the first time in the House of Lords on Monday.

Human rights groups and prominent lawyers have condemned part two of the bill, which significantly expands the role of secret courts. Opponents fear the powers will enable ministers, rather than judges, to manipulate the way evidence is withheld or presented in the courts, depriving litigants of a fair trial.

The government maintains the change will enable judges to try a greater range of national security cases and prevent claims being settled out of court.

There are intensive behind-the-scenes discussions between Liberal Democrat, Labour and Conservative opponents of the bill over how best to restrict or defeat the proposals.

The Cabinet Office's amendment is designed to buy off some of that opposition. The move narrows the scope of the bill by removing the ability of a secretary of state to extend the availability of closed material procedures to other courts and tribunals by secondary legislation. In the summer, ministers abandoned plans to include inquests in the proposals.

Explaining the latest concession, the minister without portfolio, Ken Clarke, who is piloting the bill through the Commons, said: "We have removed the secretary of state's power to extend the scope of the bill entirely. The bill is now focused even more tightly on the small but increasing number of national security-sensitive civil cases which cannot currently be heard in our courts.

"It will set to rest fears raised by the joint committee on human rights that the order-making power could have been misused, and put beyond any doubt whatsoever the fact that inquests are beyond the scope of the bill.

"This bill ends the current bar on judges taking national security evidence into account when reaching a judgment. By ensuring that evidence relating to the most secret actions of the state is argued over before a judge in a closed hearing we will ensure more scrutiny of our intelligence and security agencies, not less. "